Revisit NSIP: Is it really a non-specific disease?

Venerino Poletti​
University of Bologna,Bologna, Italy

Nonspecific interstitial pneumonia (NSIP) has long been considered a distinct histopathologic pattern within the spectrum of interstitial lung diseases (ILD), characterized by uniform interstitial inflammation and/or fibrosis. Initially described as a “non-specific” entity due to its lack of unique histological features, NSIP has since been increasingly recognized as a pattern often associated with specific clinical contexts, particularly connective tissue disease (CTD)-associated ILD, hypersensitivity pneumonitis, and drug-induced lung injury.

The historical evolution of NSIP, its pathological hallmarks, and the advances in clinical, serologic, and radiologic correlation have redefined its diagnostic value. High-resolution CT imaging features such as lower lobe-predominant ground glass opacities, reticulation, and subpleural sparing when matched with clinical context and histology, can provide a high degree of diagnostic confidence. Furthermore, data suggest that NSIP carries a more favourable prognosis compared to usual interstitial pneumonia (UIP), particularly when associated with autoimmune conditions.